JPS63209829A - Resistance weldable resin laminated steel plate and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin-laminated steel plate that can be subjected to resistance welding, particularly spot welding, and a method for manufacturing the same.

[Conventional technology]

Resin-laminated steel sheets, in which a synthetic resin layer is interposed between steel sheets, have excellent properties such as vibration distribution and noise prevention properties, and are now rapidly becoming popular for use in automobile parts, home appliance parts, construction parts, etc. be.

For these applications, resistance welding, particularly spot welding, is often used, and since rust prevention is required, steel sheets plated with zinc, zinc-iron alloy, etc., or zinc-plated steel sheets are used. Steel plates coated with rich primer-based paints are in practical use. Therefore, the resin-laminated steel sheet is also required to be resistance weldable and rust-proof.

Since resin-laminated steel plates have a non-conductive synthetic resin layer interposed between the steel plates, many attempts have been made to enable resistance welding, and some have been put into practical use.

In order to impart conductivity to the resin-laminated steel sheet, conductive particles such as iron powder, mill scale, and Kazen graphite particles having a particle size of 1/2 or more of the thickness of the layer are added to the synthetic resin layer. There is a structure that accounts for ~50 weight: t% (see 146649/1986).

In addition, spot weldable adhesive clad metal plates include stainless steel, steel, copper alloy, etc. metal plates with a plate thickness of 0.05 to 1.0U, and carbon steel (normal steel, high-grade steel) with a plate thickness of 0.4 K1 or more. A steel plate (such as tensile steel) is bonded with a resin adhesive, and the thickness of the adhesive layer is 0.5 to 1.
5 times more iron, zinc and aluminum.

Some adhesive layers contain metal powder such as copper or stainless steel (see Japanese Patent Laid-Open No. 57-51453).

Here, nine examples of carbon steel plates plated with zinc or the like are exemplified as surface-treated carbon steel plates.

[Problem that the invention seeks to solve]

However, such conventional resistance weldable resin-laminated steel sheets may have serious defects in welding quality. Namely, (1) a defect in which a hole is formed in the steel plate around the welded part of the W4 plate (referred to as a pinhole); (2)
(3) A defect in which the molten steel inside the welded part of the steel plate spews out to the outside (referred to as surface dispersion); and (3) a defect in the surface shape due to the swelling of the synthetic resin layer around the welded part of the steel plate.

The causes of these defects will be explained using diagrams.

FIG. 3 is an explanatory diagram of spot welding.

In spot welding, two steel plates 1 and 1' are placed one on top of the other, and a round bar-shaped electrode 2 and 2' is used to press the two steel plates together and energize them. 3 is heated to a molten state and welded in dots.

In the figure, 4 is a transformer, 5 is a control device, and 6 is a power source. However, when spot welding a conventional resin-laminated steel plate containing conductive particles and a normal steel plate, the processes shown in FIGS. 4(a), 4(a) and 4(c) are performed.

FIG. 4(a) shows the initial welding process, in which a resin-laminated steel plate 7 containing conductive particles and a normal steel plate 1 are placed one on top of the other, and this is pressurized with a round bar-shaped electrode 2.2'. Turn on electricity. In this case, the welding current flows throughout these steel plates. Since the synthetic resin layer 8 of the resin-laminated steel plate 7 contains conductive particles 9, current flows, but the steel plate portion 1
Electrical resistance is very large compared to 0.

Ninth, a large voltage is applied to the synthetic resin layer 8 compared to normal welding of steel plates.

Therefore, in the resin-laminated steel plate 7, although the current flowing through the entire synthetic resin layer 8 is relatively small, a relatively large current flows through the individual conductive particles 9 that carry the current, and a considerable amount of current flows at each point of the conductive particles 9. Causes fever.

FIG. 4(b) shows the middle stage of welding.
1 softens due to heat generation, and is expelled to the outside of the position immediately below the electrode due to the pressure applied to the electrode. In this case, the electrical resistance of the synthetic resin layer portion 1 is significantly reduced, the current is concentrated on the steel plate portion 11 directly under the electrode, and the voltage applied to the synthetic resin layer 8 is also reduced. Therefore, in the initial stage of welding, the conductive particles 9 of the synthetic resin layer portion 12 located outside directly under the electrode
The heat generation will also be reduced.

FIG. 4(c) shows the process at the final stage of welding, in which the resin laminated steel plate 7 containing conductive particles and the ordinary steel plate 1 are welded in a dotted manner. Symbol 13 indicates a slot (weld metal).

(1) Regarding the occurrence of pinholes, see Figure 4 (a) above.
This occurs when it takes a long time to change from the early welding process shown in FIG. 4(b) to the middle welding process shown in FIG. 4(b). That is, if the large heat generation of the conductive particles 9 continues for a long time.

The portion of the steel plate in contact with it melts, and the melting progresses further until it reaches the surface of the steel plate, spewing out molten steel and creating a pinhole.

(2) Surface scattering occurs when the surface of the steel plate directly under the electrode is melted and the molten steel inside is blown out, similar to the case of pinholes, when the conductive particles in the synthetic resin layer generate significant local heat generation. It is.

(3) Regarding defects in the surface shape due to swelling of the synthetic resin layer around the welded parts of the steel plate, as shown in Fig. 4 <&) above, of course,
Also in FIG. 4(b), the temperature of the synthetic resin layer 5 rises due to energization, so before the melt #4 is formed on the contact surface between the resin laminated steel plate and the normal steel plate.

Molten steel is formed at the joint with the synthetic resin layer, and the molten steel scatters onto the synthetic resin layer. In this case, since the molten steel has a large calorific value, the synthetic resin gasifies and the pressure causes the steel plate to swell outward, thereby reducing defects in the surface shape of the steel plate.

An object of the present invention is to provide a resin-laminated steel plate that can be resistance welded without causing one or more welding defects and has excellent rust prevention properties, and a method for manufacturing the same.

[Means and effects for solving the problem] The first invention is a resin-laminated steel sheet in which a synthetic resin layer of 10 to 500 μm is interposed between the steel sheets, and each steel sheet has a zinc-based surface treatment layer on its outer surface and a zinc-based surface treatment layer on its inner surface. has one or more layers selected from a tin layer, a lead layer, and a tin-lead alloy layer, and the synthetic resin layer has an average particle size of 0.8 with respect to the thickness (d) of the synthetic resin layer. ~1.5
It is characterized by being a resistance weldable resin laminated steel plate made by mixing and press-bonding conductive particles according to d.

The second invention uses two steel plates plated with one or more selected from tin, lead, and tin-lead alloy on one side, and mixes conductive particles between them with the plated side of the steel plates inside. The present invention is characterized in that the method for producing a resin 2-laminated steel sheet capable of resistance welding is characterized in that after a resin laminate original plate is formed with a resin layer interposed therebetween, zinc-based surface treatment is applied to both surfaces of the resin laminate original plate. As a preferred method of manufacturing, when forming a resin laminate original plate, a resin film mixed with conductive particles is adhered to the plated surface of one steel plate via a roll, and the plated surface of another steel plate is bonded to the plated surface of the other steel plate.
A method for producing a resin-laminated steel plate can be mentioned in which the exposed film surface is covered and then pressure-bonded using rolls.

The thickness (d) of the synthetic resin used in this invention varies depending on the thickness of the steel plate placed on the outside of the circle, but is 10 to 50.
A range of 0 μm is appropriate. If this thickness is less than 10 μm, lamination is difficult. If the thickness exceeds 500 μm, the effects such as allocability will remain unchanged, and it is also unfavorable from an economic point of view.

Practically speaking, a range of 30 to 100 μm is preferable.

The average particle diameter of the conductive particles varies depending on the thickness of the synthetic resin layer, but is 0.8 to 1.5 of the thickness (d) of the synthetic resin layer used.
d. If it is less than 0.8d, the average grain size is too small and welding cannot be performed satisfactorily.

If it exceeds 1.5 d, the adhesive strength between the resin and the steel plate will decrease.

Since the blending amount of conductive particles greatly affects the physical properties of the resin-laminated steel sheet, the lower limit is set at the mixing amount that ensures minimum conductivity, and the upper limit is set at a limit that does not reduce adhesive strength. Practically speaking, it is 0.2 to 3.
Favorable results can be expected by blending 0% by volume.

In this invention, each steel sheet has a zinc-based surface treatment layer on its outer surface.
The inner surface has a layer of 1 selected from a tin layer, a lead layer, and a tin-lead alloy layer.
It is necessary to have more than one layer.

The reason why each steel sheet has a zinc-based surface treatment layer on its outer surface is that zinc-based surface-treated steel sheets have excellent corrosion resistance and can be immediately applied to automobile parts, home appliance parts, etc.

Here, the zinc-based surface treatment layer is zinc or zinc-
Examples include a layer obtained by plating iron or a zinc alloy such as zinc-nickel and painting with a nine-layer or zinc rich two-timer paint.

However, it is necessary that the inner surface of each steel sheet has at least one layer selected from a tin layer, a lead layer, and a tin-lead alloy layer, which is different from the zinc-based surface treatment layer. Since resin-laminated steel sheets are generally bonded under heat and pressure using rolls or the like during the manufacturing process, metals that tend to react with synthetic resins and generate gas can cause blisters or the like on the resin-laminated steel sheets, reducing adhesive strength.

Tin, lead, and tin-lead alloys are soft metals, and they do not generate gas through reaction when heated to the extent that they are heated in the manufacturing process of resin-laminated steel sheets.

Furthermore, when zinc or zinc alloy is plated on the inside of a 2-laminated steel sheet, since these metals are generally low boiling point metals, zinc vapor is generated during energization, promoting the occurrence of welding defects.

However, with the plated metal of the present invention, such a phenomenon can be prevented.

Therefore, by having these metal layers on the inner surface of the steel plate, even if the conductive particles are hard particles such as nickel, iron, or stainless steel, these soft metals become a medium between the steel plate and the conductive particles, and the soft metal itself is conductive. This reduces the contact resistance between the steel plate and the conductive particles. Therefore, when resin-laminated steel plates are resistance welded, the electrical resistance due to the synthetic resin layer can be reduced, and as a result, defects such as pinholes, surface scattering, and poor surface shape due to blistering do not occur.

As a preferred method for manufacturing the resin-laminated steel sheet according to the present invention, one or more types selected from tin, lead, and tin-lead alloy are plated on one side of each metal plate constituting the resin-laminated steel sheet, and then those steel sheets are plated. It is necessary to form a resin laminate original plate with a synthetic resin layer interposed therebetween, with the surface as the inner surface, and to perform a zinc-based surface treatment on both sides of the resin laminate original plate.

Here, since the zinc-based surface treatment is applied to the resin-laminated original sheet, there is no need to worry about the effects of blistering caused by the presence of zinc between the steel sheet and the synthetic resin layer during the manufacturing process of the resin-laminated steel sheet.

〔Example〕

A resin laminated steel plate according to the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view showing an example of a resin-laminated steel plate according to the present invention. In the resin-laminated steel plate 20 in which a synthetic resin layer 22 is interposed between the steel plates 21 and 21', each steel plate 1! The outer surface of 1 * 21' has electrolytic zinc metal fd x s, z s', the inner surface has a tin layer j 4, 24', and the synthetic resin layer 22 has a For (d), the average particle size is 1.24
It is made by mixing and press-bonding nickel particles 25.

In this case, a lead layer or a tin-lead alloy layer can be used instead of the tin layer. Moreover, a tin layer, a tin layer, and a tin-lead alloy layer can also be used as a multilayer.

In addition, instead of the electrogalvanized layer, we use a galvanized zinc-iron alloy plating layer and an electrolytic zinc-nickel alloy plating layer.

Alternatively, it is also possible to use a layer coated with a zinc-rich brimer type molding agent.

Next, one example of the method for manufacturing a resin-laminated steel sheet according to the present invention will be explained with reference to the drawings. Figure 2 shows the manufacturing process of a nine-resin-laminated steel plate in which a synthetic resin layer containing nickel particles (average particle size 1.2 d) is interposed between a steel plate having a galvanized layer on its outer surface and a tin-plated layer on its inner surface. The steel plate 26 shown in FIG. Next, the steel plate 28 plated with tin on one side is heated in a heating furnace 29 with the plated side facing upward, and a synthetic resin film 30 containing nickel particles (average particle size 1.2 d) is coated on the plated side via a roll 31. The steel plate with a synthetic resin film glued on one side is heated in the heating furnace 2.
9, the exposed film surface is covered with the plated surface of another steel plate 28' whose one side is tin-plated, and the resin laminate original plate 32 is formed by pressing it with a roll 30. do. After that, resin laminate original plate 3
Both sides of 2 are plated with an electrolytic zinc-nickel alloy using a horizontal electroplating device 33.

Table 1 shows the conditions and product characteristics of the resin-laminated steel sheet of the present invention manufactured by the resin-laminated steel sheet manufacturing process shown in FIG. 2.

Table 1 As is clear from Table 1, the adhesion strength is similar to that of a normal resin-laminated steel sheet (containing no conductive particles), and the electrical resistance is also comparable to that of a zinc-plated steel sheet without a synthetic resin layer. Small values similar to were obtained, and spot welding did not result in defects in weld quality.

Next, the results of an experiment to determine the presence or absence of defects in welding quality (defects in surface shape due to pinholes, courtesy cracks, and blisters) when spot welding the resin-laminated steel sheets of the present invention will be described.

"Experimental Example" For spot welding, a single-phase AC spot welding machine as shown in Figure 3 was used, and the electrode tip diameter was 60mm. [Extreme pressure 250~
A combination joint of the resin-laminated steel sheet of the present invention and a conventional steel sheet of the same type was welded under the conditions of 2 energization times of 10 2 with a current just before the interface would cause expulsion. After welding, the defects in the welding quality described above were examined, and those with no defects and sufficient joint strength were evaluated as "good", and those with no defects were evaluated as "poor".

As a comparative example, when there is no metal Φ on the inner surface of the steel plate (Al 3 ), the average particle size of the conductive particles is 0.8 to 1.
．． If the value exceeds 5 d (d is the thickness of the synthetic resin layer),
ff1l 5 , Al 6 , amount of conductive particles added (
When the volume %) was out of 0.2 to 3 maoL%, A14 was used, and the other conditions were the same as in the experimental example. The experimental results are shown in Table 2.

As is clear from Table 2, if the resin-laminated steel sheet of the present invention is used, no defects in welding quality will occur during spot welding.

In the above experiment, a resin-laminated steel plate electrogalvanized was described, but it goes without saying that the same results can be obtained with a resin-laminated steel plate coated with a zinc chloride solimer paint.

Furthermore, the resin laminated steel sheet of the present invention is of course applicable to resistance welding such as seam welding, without being limited to the spot welding described above.

In addition to the method shown in the above example, the resin laminate original plate can be formed by pressing a synthetic resin film onto the plated surface of a steel plate using a roll, and then uniformly applying conductive particles thereon. After spreading, cover with the plated surface of another steel plate, or coat the plated surface of one steel plate with conductive particles made low in viscosity by heating or diluting with solvent, and then apply 9 synthetic resin. , a method of covering with a plated surface of another steel plate, etc. may also be used.

〔Effect of the invention〕

The present invention provides high corrosion resistance by forming a zinc-based surface treatment layer on both sides of a resin-laminated steel sheet, and a soft metal layer of tin, lead, or tin-lead layer on the inner surface of each steel sheet constituting the resin-laminated steel sheet. When welding with more resistance, choose
The function of the conductive particles contained in the synthetic resin layer interposed in the resin-laminated steel sheet can be fully exhibited, and the contact resistance of the synthetic resin layer can be reduced, so that the electrical resistance of the resin-laminated steel sheet can be reduced. As a result, the resin-laminated steel sheet of the present invention is highly effective in enabling resistance welding, particularly spot welding, without causing defects in welding quality (such as pinholes).

Further, according to the method for manufacturing a resin laminated steel sheet of the present invention,
Since zinc-based surface treatment is applied to the resin laminate original sheet, a layer of tin or the like can be formed completely independently on the inner surface of the steel sheet that makes up the resin laminate original sheet without being affected by the zinc-based surface treatment, which is practical. The effect is large.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a resin laminated steel plate according to the present invention.
Fig. 2 is a schematic process diagram showing one example of manufacturing the resin-laminated steel sheet of the present invention, Fig. 3 is an explanatory diagram of general spot welding, and Fig. 4 (,) is a conventional welding process containing conductive particles. A schematic explanatory diagram showing the initial welding process when spot welding resin-laminated steel plates, Figure 4 (b) is a schematic explanatory diagram showing the middle welding process, and Figure 4 (, ) is the final welding process. FIG. 20...Resin laminated steel plate, 21.21'...Steel plate constituting the resin 2-laminated steel plate, 22...Synthetic resin layer, 23, 23'...Zinc-based surface treatment layer (electrogalvanized layer) , 24.24'... Layer consisting of at least one of a tin layer, a lead layer, and a tin-lead layer (tin layer), 25... Conductive particles, 26... Steel plate, 27... Vertical type Electroplating device, 28...Steel plate plated with tin on one side, 29, 29
'...Heating furnace, 3σ...Synthetic resin film, 31.
31'...o-ru, 32... resin laminate original plate,
33...Horizontal electroplating device. Figure 4 (a)

Claims (3)

[Claims] (1) In a resin-laminated steel plate in which a synthetic resin layer of 10 to 500 μm is interposed between steel plates, each of the steel plates has a zinc-based surface treatment layer on the outer surface, and a tin layer, a lead layer, and a tin-lead alloy layer on the inner surface. The synthetic resin layer includes conductive particles having an average particle size of 0.8 to 1.5 d relative to the thickness (d) of the synthetic resin layer. Resistance weldable resin laminated steel sheet that is crimped. (2) Two steel plates plated on one side with one or more selected from tin, lead, and tin-lead alloy are used, the plated sides of the steel plates are on the inside, and conductive particles are mixed between them. After forming a resin laminate original plate with a resin layer interposed,
A method for producing a resin-laminated steel sheet capable of resistance welding, characterized by subjecting both surfaces of the resin-laminated original sheet to zinc-based surface treatment. (3) When forming a resin laminate base plate, a resin film mixed with conductive particles is adhered to the plated surface of one steel plate via a roll, and the exposed film is bonded to the plated surface of another steel plate. 3. The method of manufacturing a resistance weldable resin-laminated steel sheet according to claim 2, wherein the resin-laminated steel sheet is formed by covering a surface thereof and then pressing the sheet with a roll.